In message <25F0B21A-0319-45E3-9DBF-9906CB77AC6C@kapu.net>, Michael J Wise writ es:
On Jul 27, 2012, at 6:40 PM, David Miller wrote:
MX records don't "chain".
But they do, "Expand". And I can think of a way whereby if an MX record referenced itself, = *AND* included something extra =85 (did you see the something extra?)
That it would be possible (and I'm not saying this is what is happening, = but =85 it could be) =85 That an internal process could go resolving MX records, and adds them = all to an internal table, until it figures it's got 'em all=85
"Gotta Get 'Em All!"
=85 and maybe, just maybe =85 it exhausts the table space, and gives up, = and tries the A record.
I'm not saying this would be "Standard".
It would be broken. MX records say which machines are set up to receive email for a domain. Delivering it elsewhere, unless explicitly overridden (e.g. smarthost), is a security flaw in the MTA.
I'm not saying this is the best, or perhaps even an acceptable way to do = it. Or that it is in fact what is happening.
But the config looked weird, and I can imagine =85 a system being = written as described =85 and breaking just this way given that MX = configuration. I can imagine Test =85 not catching it.
Aloha, Michael. --=20 "Please have your Internet License =20 and Usenet Registration handy..."
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka@isc.org